The present invention relates to joint forming devices and systems are used in the construction industry to create separations in concrete slab applications to allow for expansion and contraction of the concrete due to seasonal variations in temperature. The present invention relates to a novel joint forming system that maintains its ability to retain a joint separation well and is made of materials that resist deterioration against a wide variety of joint filling agents and solvents.
Joint forming devices and systems of the type described above are not new per se. A presently known two-piece joint forming device and system comprises a base or retainer section of generally rectangular form and of a predetermined width and a tear-off strip or section of a width generally the same as the base and connected and spaced from the base by a continuous fracturable tear-off section of a significantly smaller cross-wise width than the base or tear-off section.
It has been found when these presently known devices and systems are used in typical applications and positioned where an expansion joint is desired before pouring concrete the concrete tends to deflect or laterally displace the tear-off section and thus when the tear-off section is removed, the well formed for a joint filling agent is not of predetermined, prerequisite dimension. It has been found that if the well is not reconfigured, that there is a risk of damage to the concrete under certain temperature conditions which may result in buckling of the concrete at the well site. Accordingly, it is necessary to reconfigure the well by use of cement saws or the like.
The non-absorbent, compressible joint forming device and system of the present invention are commonly used in expansion or contraction joints and isolation joints of sidewalks, driveways, highways, runways, parking decks, and other applications where concrete slabs are used. These systems are currently marketed under the product names of Poly Strip, Poly Strip HT, Poly Joint, and Poly Joint HT. An objective of the present invention is to provide a joint forming system whereby lateral instability of the tear-off strip is eliminated.
Another objection of the present invention is to provide a joint forming device and system characterized by novel features of construction and arrangement whereby the tear-off section by reason of the fracturable bridge arrangement does not tilt during a cement pouring operation to form a joint, thereby ensuring a well of proper dimensions when the tear strip is removed and thereby also overcoming some of the disadvantages of the prior art where redressing of the well was required before application of the joint filling agents or the like.
A further objective is to ensure sealant adhesion to the joint surfaces only and reduces clean-up time before sealing.
Yet another objective of the present invention is to provide a joint forming system that is virtually inert and therefore compatible with silicone, butyl, polysulfide, acrylic, polyurethane and most other cold sealant compositions and will resist gasoline, oil, and many other solvents. The material is effectively odorless, will not stain, absorb moisture or adhere to sealant materials and is non eroding.
Still another objective of the present invention is to provide a joint forming system that is compatible with most rubber, asphalt and biodegradable polymer thermoplastics compounds and are more appropriate in applications such as acid proof flooring, airport runways, sewage treatment facilities and many other circumstances requiring high chemical resistance.